This invention relates generally to a pipe lining technique, and more particularly to a branch pipe lining bag for lining an aged or defective inner wall of a branch pipe joining a main pipe and also to a method for lining these pipes by using the branch pipe lining bag and a main pipe lining bag.
When an underground pipe, such as a sewer pipe, becomes defective or too old to perform properly, the pipe is repaired and rehabilitated without digging the earth to the pipe and disassembling the sections of the pipe. This non-digging method of repairing an underground pipe has been known and practiced commonly in the field of civil engineering.
The pipe lining method utilizes a sufficiently long tubular flexible liner bag made of a resin-absorbent material impregnated with a curable liquid resin such as thermosetting liquid resin, and having the outer surface impermeably covered with a highly air-tight polymeric film. The tubular pipe lining bag is inserted into a pipe to be repaired by means of a pressurized fluid, like air or water, such that the pipe lining bag is turned inside out as it proceeds deeper in the pipe.
More particularly, the tubular flexible liner bag is closed at one end and open at the other. The tubular flexible liner bag is first flattened. Then, the open end of the tubular liner bag is spread open and hooked (anchored) at the end of the defective or aged pipe in a manner such that the opened end of the liner bag completely and fixedly covers and closes the pipe end. A portion of the liner bag in the vicinity of the pipe end is pushed into the pipe so as to create an annular pocket. Then, the pressurized fluid is applied to the annular pocket of the tubular liner bag whereupon the fluid urges the tubular liner bag to enter the pipe.
Since one end of the tubular liner bag is hooked at the end of the pipe, it remains there while the rest of the flexible liner bag is turned inside out under fluid pressure as it proceeds deeper in the pipe. (Hereinafter, this manner of insertion shall be called "everting".) When the entire length of the tubular liner bag is everted (i.e., turned inside out) into the pipe, the everted tubular liner bag is pressed against the inner wall of the pipe by the said pressurized fluid or by an inflatable pressure bag which is newly inserted inside the everted tubular liner bag, and the tubular flexible liner bag is hardened as the curable liquid resin impregnated through the thickness of the liner bag is cured (by heating in the case a thermosetting resin). Thereafter the closed end of the liner bag is cut off. It is thus possible to line the inside wall of the defective or old pipe with a rigid liner without digging the ground and disassembling the pipe sections.
This pipe lining method is similarly applicable to a branch pipe that is in fluid communication with a main pipe such as sewer pipes. We have formerly proposed a branch pipe lining method wherein a branch pipe is internally lined with a branch pipe liner bag having a flange at its opening end. More particularly, according to this method, the branch pipe liner bag is positioned in the main pipe and the flange of the branch pipe liner bag is fitted closely on the periphery of the opening, which is made in the wall of the main pipe and defined by a lower end of the branch pipe. The branch pipe liner bag is, then, everted into the branch pipe under fluid pressure so that the liner bag goes up toward the surface of the ground. When the eversion is completed and the liner bag is closely pressed against the inner face of the branch pipe, the curable liquid resin impregnated through the branch pipe liner bag is hardened by heating or some other procedure.
After the branch pipe is internally lined by this branch pipe lining method, the main pipe is then lined with a main pipe liner by the conventional pipe lining method as described above. However, since this main pipe liner closes the opening to the branch pipe, it is necessary to bore the main pipe liner so as to connect the main pipe and the branch pipe with each other.
If, however, the inner diameter of the main pipe is smaller than 800 mm or so, a person cannot enter the main pipe and it is necessary to use a borer robot with a cutter, which is introduced into the main pipe in place of a person, by remotely controlling on the ground to bore the main pipe liner.
However, it requires much skill to properly control the borer robot in such an operation, and when the operator is not very careful, the robot's cutter may attack the flange and other portions of the branch pipe liner which are not intended to be removed. When such inadvertent cutting causes breaks, ground water would penetrate through them into the pipes to cause problems. In certain special cases wherein a connection of the branch pipe to the main pipe is of such configuration that renders the boring difficult, damages on the branch pipe liner by the cutter were unavoidable.
It was conceived, accordingly, to protect a periphery of the branch pipe liner with a protective member at a portion adjacent to the flange, after lining of the branch pipes. However, if the main pipe has an inner diameter less than 800 mm that allows no person to enter thereto, it is impossible to attach the protective member by person.
It is, therefore, a principal object of this invention to provide an improved branch pipe lining bag.
It is another object of this invention to provide a branch pipe lining bag which can be equipped with the protective member simultaneously with completion of the branch pipe lining, irrespective of the inner diameter of the main pipe.
On the other hand, the portion of the main pipe lining bag that needs the boring shapes an arc or curved face. Due to this shape, the cutting depth varies corresponding to diameters of the main pipe and the branch pipe and further to cutting points around a periphery of the branch pipe opening. As a result, the cutter enters too deeply into the branch pipe lining bag. This requires the protective member to be between 20 mm and 100 mm in height and to push such a protective member into the branch pipe.
However, the protective member is made of metal or hard materials. Also, if, as shown in FIG. 16, the branch pipe 111 is connected to the main pipe 110 with an angle (for example, =45.degree. or 60.degree.) or, as shown in FIG. 17, the branch pipe 201 is connected to the main pipe 210 through a 45.degree., 60.degree. or 90.degree. elbow, it is impossible to set such a long height protective member completely.
It is, therefore, a further object of this invention to provide an improved pipe lining method.
It is still further object of this invention to provide a pipe lining method whereby the main pipe lining bag can be bored without any damage irrespective of both the main pipe diameter and the branch pipe diameter or any connecting situations.
The above and other objects, features and advantages of this invention will become apparent from the following detailed description of the preferred embodiments thereof when read in conjunction with the accompanying drawings.